Velocity modulated electron device



Sept. 2, 1952 COETERlER 2,609,521

VELOCITY MODULATED ELECTRON DEVICE Filed July 16, 1946 INVENTOR. FREDERZKCOEIERZER Patented Sept. 2, 1952 2,609,521 y. VELOCITY MODULATED ELECTRON Davies UNITED STATES PAT N QQ 'i Frederik Coeterier, Eindhoven, Netherlands; asv l Signor to H'atrtfordNational Bank andiTriis't' Company Hartford (301111., as trustee Applicaticn July 16, ie iaseriei No. 43078 lathe-Netherlands April 6 19% J J sjeetijen r biie-Law 690, August 8', I946 H Patent expires Api' il- 6, 1-963 This invention relates to a device in which an electron" liairii ispro'duced' inside an exhausted vsselg thevelocity of theelectrons in the beam l i-ig'h iredutency withthe aid ot'an' electrode syswhereupon the variations" in: velocity are enverte'd intd-ifali'ialtions iri intensity.

A; evfeeer Ema p'ermits of amplifying uitrahign frequency osciuati'ons" which are supanes 6 the electrode? system for the velocity contrilan Whichat this place bring about a variat "eed of the electrons in the beam,it 5 fig oss'ibl foitli-dniplified oscillationsto be denvedfromaseccnd electrode system which is lccated aftei the device for converting variafidris velocity into variations in intensity and which is tuned to the frequency of the first e1ect'r'od'sys'tem. Itis alternatively possible for the second electrode system to be coupled to the con trol elctrodesystem in such manner that the device operates as a generator. In this case the frequency of the: oscillations produced is determined 59 the dimensions'iof the oscillatory syscdnsti'tuted by the control-electrode system, tne'seeond: electrode system and the feed-back line. The high-frequency oscillation energy to be iitiliz'ed' maybe taken inductively or capacita'tivlyfrom the oscillatory system, or be taken d iictly from: the electronbeam by means-of a third electrode system which is located onthat side of the oscillatory system which is remote from-the: cathode. In this case the third electrcde systememay' be.tunedveither to the irequency of the: oscillationszprodiiced by the oscillater-y system, or: to a. higher harmonic thereof.

Furthermore; l. iii'isvpossible that the device" for converting variation'srin "velocity into variations in} intensity;. which isi usually constituted by an electrode" embracing" an equipotential space of a definiteil'ength,:is;constitutediby a perforated deceleratingi-fi'eld electrode which allows the passagetof; electronssat 1. highly'retarded velocity and which. like the electrode? embracing the. equinotential space. has: for its purpose" to hold u the electrons retardeddn;velocity-in the control electrode I system, that is to. say to give 3 them ;a longer transit time thanthelelectrons: accelerated; in the controlrsystem, sohthat by: .meanslof overtaking a grouping, action is'obtained. The device for the; conversion, of. [variations in velocity into variations in intensity will"hereina fter be referredfto' as drift" device or drift electrode.

A Theknown' devices of the above described kind always comprise means: or'producing' an electron beam which'isunambiguouslydeterminedin velo'eity or,- after-having passed through the veloc 7 Glaims. (Cl. 351 -42) ity control system; is unambiguously determined in its average velocity by'the direct-voltages sup plied to the variousel'ectrodes. l

In the device according to'the mventi'on'the electron beam entering the control-system is con stituted by a mixture, preferably uniformivdf groupsof electrondoriginatirig from at leastitwo electron sources. It thus becomes p0ssi'ble td cause the groups of electrons" originating from' at control system at difierentvelocitiesthe differ ence of velocity or'fdefined more sharply; the difierehceof kinetic; energy can preferably be? controlled within broad limits.

the cathode andtFrecontrol-system; wjhich 'has the capacity of emitting secondary electronsiand which allows the passage of electrons? With'the' aid of this deviceitmay be attained'thafthe groups of electrons originating from the cathode" and from at least one electrode having the" ea pacity of emittingsecor'idary electrons enter the control system at'different velocitiesby supplying to these" electrodes avoltag positive relatively to the cathode; Since the electrons disl odg'e'd'afi this electrode, preferably grid=shaped by means of secondary emission substantially emanatdat avelc'city zero, the electron beam; after 'liialving passed through this'grid, will consist'of' a hiinio geneou's rnixture'of electrons having two difierent velocities, viz. 1 primaryelectronswhich have left the cathode with a velo'city zeroand which at the" place of the grid" are propagatingat a velocity determined by the positive grid voltage" and 2 secondary electrons which at 'thisflplace" begin with their'path at" an initial velocity" zero) The electron groupsorigi'riating from different sources are propagated along the control systemwhere each of them is modulated in'velocity andw'hereafter all of thein are" subjected 'indepnd ently' of on another to 'the action of a'fdrift" electro de; In this"case"'different "cases' m" 'y'arisa} which will l'ijereiiiaft't" be' ekpla'inedfie at'eiy'l" The invention will be described in greater" de tailwith refereri e" to="the-appeiidec drawing id which: Figure" 1 sc matieeuy illustrates one-"foimefdevice in accoidarroeWith theirive'ntio n.

Fig. 2 graphicallyillustrates thevoltage relationship existing "the device indirectly heated cathode 2, a secondary emis- I sive cathode 3 in the form of a grid and a collecting electrodes. A voltage preferably adjustable and positive relatively to the cathode 2 is supplied to cathode 3 by a source of supply 5. The primary electrons emitted by cathode 2 and the secondary electrons dislodged at cathode 3 by a number of the primary electrons pass successively through a control-electrode system constituted bye, control electrode 6 and two boundary electrodes 1, a drift electrode 8, and a second electrode system constituted by an energy abstracting electrode 9' and two boundary electrodes l. highvoltage which is positive relatively to cathode 2 and which originates from a source of supply II is supplied to the electrodes 6, 1,8, 3 and 10. The supply sources 5 and II are shunted bycondensers I2 and I3 respectively, which constitute short-circuits for ultra-high frequencies.

:In the described device the electrons entering the control systems 6, I will be constituted by a uniform mixture of electron groups of primary and secondary electrons, which electron groups have different velocities. The difference in ve-,

locity is determined bythe value of the source of supply I When ascontrolfios'cillation of ultrahigh-ire quency is supplied to the control electrode 6, the electrons of the two groups of electrons entering the control system will be varied in velocity, the

electron groups varied in *velocity subsequently being subjected to'a grouping action in the drift space of electrode 8.1 Inthis case the intensity maximaof the secondary electrons dislodged at cathode 3, due to the smaller average velocity at which they enter the'control system, will lag on the correspondingintensity maxima of the primary electrons emitted by cathode 2, so that the intensity maxir'na'of the secondary electrons pass through the second electrode system 9, I0 some time after the intensity maxima of the primary electrons. By means of a correct adiustment of the difference in velocity between the primary and the secondary electrons entering the control system,'by means of source of supply 5, it may be ensured that the intensity maxima of the pri- 55 mary electrons and those of the secondary electrons pass through the energy abstracting system 9, ill with a time difference corresponding to half the time of oscillation of the control oscillation.

It is thus ensured that at the point of electrode system 9, l0 it is possible to abstract energy from the beam, the frequency of which is equal to double the'frequency of the control oscillation. To. this end an oscillatory circuit l4 tuned to the firstharmonic of the; control oscillation is interposed between. the electrode 9 and the boundary electrodes I 0; By giving the amplitude of the controlvoltage in connection with the'length of the driftelectrode such a value that'a complete conversion of variations in velocity into variafunction of time by curves a and b respectively. Curve 0 represents the resulting'voltage as a function of time.

In the described device electrode 3 is preferit which is located between the drift electrode 8 and the energy abstracting system 9, l0 and which i coupled to the control system 6, '1 via a feed-back line l8 including an oscillatory circuit l1.

With an adjustment of the diiference in aver age velocity between the two electron groups entering the controlsystem which is suchthat the consecutive density maxima of the-onegroup enter the electrode system 9, [0 a half period of. oscillation after those of the other group, the density maxima will pass; through theelectrode system 15,16 a, short time aftereach other (that is tosay after a time which is short relatively; to the period of oscillation of the control voltage set up at the control system? Consequently, the energy abstracting electrode I5 willchiefly abstract energy'having the frequency ofthe con; trol oscillation of the beam. which energy is fed back to the control system 6, '1 via the feed-back line I8.

the voltage induced in electrode libythe primary and the secondary electrons; The resulting voltage as a function of time is represent-edbycurve 0. Since the complete conversion orvariations in speed into variations in intensity has 1 preferably not taken place before'the' electrode system 9, II) was entered, the. amplitudeof the voltage induced 'in electrode, 15 15 preferably? smaller than the amplitude of the voltage. tof" harmonic frequency which is takenfrom-the. electron beam by means of the electrode sysjterm 9, l0.

Another form of construction anaemiccording to the invention is shown in: Fig; 15. Inthis device the drift electrode is constituted by a;

perforated decelerating-field electrode 19' which has supplied to it a voltage which is positive rela-'- tively to the cathode but which is negative rela tively to grid 3. The distance between the wires of grid 3 is preferably so large that a but small.-

fraction of the electron beam entering the cone trol system 6, I is constituted by secondary electrons comparatively slow. All the primary electrons controlled in velocity pass through decelcircuit firebpredtctne contrdi plified oscillations areii takenfo reasons-elect 0d y is emphatica y' po 1; d out thar; the ticniisbyno' mea'nsim te" to the us'" of ne'er? more" electrodes nav n'g secondary electrons; invention may alter nativeiy u 1 -z icathode systems which are relatively insulated. For example; one orl mdr cathode surfaces may be shaped in the form o f concentric rings embracing another" circulascathode surface. Such a modification of the device of the q-invention is shown in Fig. '6 wherein the source ofxprimary electrons constituted by the cathode is concentrically surrounded by two secondary emissive sources" constituted by the secondary emissive cathodes 3 -a'nd 3-" inlthe iorni concentric ings surrounding the cathode-2, In Jdevice it may be ensured that the groups of letior igiiiating from diiferent" cathodes 1- aces enter the: control system 6, J atidiiferent ylbcia ties? by giving the cathode-surfaces different potentials!" w What I claim is:

1. An electron discharge device system comprising, an electron source of a beam of primary electrons having a given velocity, an electron permeable control electrode system in spaced relation with said electron source for producing cyclic variations in the velocity of the electrons of a composite electron beam to thereby produce intensity variations of the beam at a point spaced from said control electrode system, an electron permeable secondary emissive source of electrons having a velocity diiferent from the electrons of said primary electron source interposed between said source of primary electrons and said control electrode system to mix said secand group of electrons with said first group of electrons to form a composite electron beam directed towards said control electrode system, and energy collecting means in the path of the electrons of the said composite beam and arranged at said spaced point.

2. An electron discharge device system comprising, an electron source of a beam of primary electrons, an electron permeable control electrode system in spaced relation with said electron source for producing cyclic variations in the velocity of the electrons'of a composite electron beam to thereby produce intensity variations of the beam at a point spaced from said control electrode system, an electron permeable secondary emissive source of electrons interposed between said first source and said control electrode system to mix said second group of electrons with said first group of electrons to form a composite electron beam directed towards said control electrode system, means to apply a positive potential to said secondary emissive source relative to said primary source to produce first and including a: second sbii rceto generate a second group- 6f electrons raving aven my smarter from-"the velocity oftheei'e'ctr st ea from said electron permeabl iectron cc iecto electrode spa'ceu rronr y re variatibn producing inearrsnn he pat an output electrode" system interposed. n the eiectron ath' between said drifit electro I the bolle'ctor electrode "z-rorr extracting from me intensity varied beam energyat 'a harmonic f sai'dgiven'freq 3D r charge device; systeml eo'mding a first? sourceito" gerr-v er'at aib'eam or first grou er eiradwshaving ag err-velocity, means' including a secorid sburce nt' said li rst source to generate second grou mr electrons having a' velocity diif'er'ent the neutrons cri sai-d: rst group a'nd to m1 mneeiect with tne-electro s or said fir's't' group to form a composite electron beam, a control electrode system in the path of the composite beam to produce cyclic variations in the velocity of the electrons of said composite beam at a given frequency to thereby produce intensity variations in said composite beam at a point spaced from said control electrode system,

an electron collector electrode spaced from said control electrode system in the path of said composite beam, a drift electrode interposed in the electron path between said control electrode system and said collector electrode, a first output electrode system interposed in the electron path between said drift electrode and the. collector electrode and coupled to said control electrode system, and a second output electrode system interposed in the electron path between said first 'output'electrode system and said collector electrode for extracting from the intensity varied beam energy at a harmonic of said given fre quency.

5. An electron discharge device system comprising means including a primary source to generate a beam of a first group of electrons /having a given velocity, means including a secondary emissive source adjacent said primary source to generate a second group of electrons having a velocity difi'erent from the velocity of said first group and. to mix the electrons of said first and second groups to form a composite electron beam, an electron permeable control electrode system in the path of the composite beam to produce cyclic variations in the velocity of the electrons of said composite beam to thereby produce intensity variations in said composite beam at a point spaced from said control electrode system, the number of electrons of said first group entering said control electrode system beingsubstantially equal to the numberof electronsof said second group entering said control electrode-.,system, an electron collector electrode spaced from said control electrode system in the path o t-the composite-beam, a drift electrode interposed-in the electron path between said control electrode systemand said collector electrode,

' erate 'a- 'beam ofa first groupof electrons having agivenvelocity; meansv including a second source adjacent said first source to generate a second groupof electrons having a velocity smaller than the velocity of the electrons ofsaid first group to {0111118, composite-beam, an electron permeable control electrode-system inthe path of the compositebeamj to produce cyclic variations in the velocity: of, {the electrons of said, composite beam topthereby produce intensity variations in; said composite beam at apoint-spaced from saidcontrol electrode system, the number of electrons of said ,firstgroup entering said control electrode system being greater than the number of electrons of said second group entering said control electrode system, a collector electrode spaced from said control electrode system in the path of thecomposite beam, adrift electrode interposed in the electron path'between said control electrode system and said collector electrode, means to apply to said drift electrodea decelerating potentialfor said lower velocity electrons, and an output electrode system interposed in the electronrpath between said drift electrode and the collector electrode for extracting energy Irom the intensity varied beam. i

7. An electron discharge device comprising,

means including a first cathode to generate a beam of a. first group-of primary electrons having a given velocity, means includinga second oath,- ode, adjacent said; first cathode, concentrically surrounding said first vcathodeto generatea second group of electrons having a velocitydif ferent from the electronslof said first group and to -mi x the, electrons of said first; and second groups to; form a composite electron beam, energy collecting means in the pathof the electrons from the said first cathode and said second cathode, and means arranged-'in-the path of the composite beam and interposedbetween the said cathodes and said energy collecting means ,to produce cyclic variations in the velocity of the electrons of said composite beam to thereby produce intensity variations in said composite beam at a point'spaced from said cyclic variation'producing-means. a Y

c I 1 ana-mess CI' IE D l 'The following references are of record' i f .file of this patent:

UNIT D STATES, 1'

RF'REDERIK oon'rERInR.

Goodall Feb; 25,1947 

